Paper product and method of making same



Patented June 7, 1927.

UNITED STATES.

VKPATENTA OFFICE.

JAMES MOINTOSH, OF NORRISTOWN, PENNSYLVANIA, ASSIGNOR TO DIAMOND STATEFIBRE COMPANY, OF BBIDGEPORT, PENNSYLVANIA, A CORPORATION 01' DELA- IWARE.

No Drawing.

Impregnated and laminated materialshave been made by passing themanufactured paper through a bath of synthetic resin solutions and thelike, and thereafter heating the sheets under pressure to giveuniformand highly polished surfaces.

I have found that if a cellulose ester is added to the pulp or ragfibres during proc-' essing, that treatment under heat and pressuresubsequent to the completion of the paper will give a product resemblingthat 25 made by impregnation. My process ives a product in which thecellulose ester is intimately and uniformly dispersed throughout thefibres as well'as upon the surface, resulting in a more water-proof andmore durable product than has previously been possible by impregnation.A further advantage of my process resides in the elimination of one stepin the .process, to wit, that of impregnation. r

The term cellulose ester embraces tha class of compounds which areformed by the action of acids on cellulose, and includes the celluloseacetates and cellulose nitrates but due to the non-infla1nmable natureof the former, I prefer to use that compound. In carrying out myprocess, I add the solid ester to the pulp and rag fibres in the beatertogether with the filling, sizing and dyeing compounds. The action ofthe beater commlnutes the cellulose ester and uniform ly disperses itthroughout the mass. The percentage of the cellulose compound added deends upon the'properties desired in the finished product. A relativelylow ercentage, that is from to (base on the finished product), will givea paper product after treatment, as hereinafter described which will besomewhat "flexible, while a productcontaining about 50% of the cellu-PAPER PRODUCT AND METHOD OF MAKING SAME.

Application filed March 2, 1826. Serial llo. 91,815.

lose ester will resemble vulcanized fibre and will be hard, compact andmechanically strong.

' The paper is processed in the usual manner, since the-presence of theester has no effect on the materials entering into the paper nor on themechanical operations. After the paper has left the Fourdrinier machine,it is ready to be vulcanized, that is to be sub- .jected to heat andpressure. The single sheets, if they are of the desired thickness, arevulcanized er se, ora laminated product is built up y su erimposing onesheet upon another until tie requisite thickness is obtained. In eithercase, the heat and pressure step is accomplished in the same manner.

The sheets are placed between the heated platens of a suitable presswhereby they are subjected to pressure such as one thousand 75 poundsper square inch at a temperature of one hundred and twenty-five poundsof steam. This heat and pressure are maintained for a time sufiicient tocause the cellulose ester to fuse throu hout the fibrous mass and toflow complete y over the surface,

forming a continuous coating. If the platens are highly polished, therewill result a .smooth, uniform and highly polished coating of the esteron the surface of the fibrous material. The cellulose ester binds thesheets into a compact inseparable body.

The paper sheetscontaining the cellulose acetate after they leave theFourdrinier machine may be parchmentized in the. usual manner, in whichcase, for example, the sheets may be passed through a bath of 70-72 Baumzinc chloride at a temperature of 100 to 125 F. whereupon the paper.sheets will be changed to a vegetable parch- I ment membrane and maybe, if desired, superimposed to obtain the required thickness. Thearchmentizing agent is freed from the membrane by leaching in asuccession of water baths, called puring baths. parchment membranecontaining the cellulose acetate is dried then subjected to the heat'and pressure treatment hereinbefore described, whereupon thecelluloseacetate will fuse throughout the product .and render itmorewater-resistant and more durable.

Instead of treating the parchment membraneafte'r puring by heat and.'ressure, I

The

have found that satisfactory re ts are obtained if the membrane takenfrom the puring bath is immersed in a solvent for the cellulose acetate,such as acetone, the solvent will enter the pores displacing the waterand causing a film of the acetate to form throughout the product. Uponevaporation of the solvent, a water-resistant fibrous sheethomogeneously impregnated with cellulose acetate will result.

The above described materials are available for a wide variety of uses,such as a raw material from which machine elements such as gears,pulleys, or the like may be formed or machined, and also as anelectrical insulator, especially in the construction of switchboards forradio apparatus, a material for making containers, or other structureswhich it is desirable shall be unafiected by moisture, oil or otherliquids. It is also applicable for the surfaceveneering of Wood orcardboard.

Considerable modification is possible in the processing of the paper andin the percentages of cellulose acetate used with no departure from theessential features of the invention.

I claim:

1. The process of making a paper product which comprises adding acellulose ester to the paper and rag fibres prior to the Fourdriniermachine, processing the paper in the usual manner, parchmentizing thepaper,

and thereafter subjecting the sheet to heat and pressurev to cause thecellulose ester to flow throughout the mass.

2. The process of making a paper product which comprises addingcellulose acetate to the paper and rag fibres prior to the Fourdriniermachine, processing the paper in the usual manner, parchmentizing thepaper, and thereafter subjecting the sheet to heat and pressure to causethe'cellulose acetate to flowthroughout the mass.

3. The process of making a paper product which comprises adding acellulose ester to the paper and rag fibres in the beater,

processing the paper in. the usual manner,

parchment-izing the paper, superimposing the sheets to obtain thethickness desired, and thereafter heating the same under pressure tocause the cellulose ester rto flow? throughout the mass. I

4;. The process of making a paper product which comprises addingcellulose acetate to the paper and rag fibres prior to the Fourdrinier'machine, processing the paper in the usual manner, parchmentizing' thepaper,

superimposing the sheets to obtain the thickness desired, and thereafterheating the same under pressure to cause the cellulose acetate to flowthroughout the mass.

' 5; The process of making a paper product Which comprises adding acellulose ester to the paper and rag fibres prior to the Fourdriniermachine, processing the paper 'in the usual manner, parchmentizing thepaper,

leaching out the parchmentizing agent with water, and thereaftersubjecting the parchmentized sheet to the action of a solvent for thecellulose ester whereupon the solvent displaces the water in the poresand causes a film of cellulose ester to form in the parchment membrane.-

6. The process of making a paper product which comprises addingcellulose acetate to the paper and rag fibres prior to the Fourdriniermachine, processing the paper in the usual manner, parchmentizing thepaper, leaching out the parchmentizing agent with Water, and thereaftersubjecting the parchmentized sheet to the action of a solvent for thecellulose acetate whereupon the solvent displaces the water in the poresand causes a film of the cellulose acetate to form in the parchmentmembrane.

7. The process of making a paper product which comprises adding'acellulose ester to the paper and rag fibres prior to the Fourclriniermachine, processing the paperin the .usual manner, parchmentizing thepaper,

superimposing the sheets to obtain the thickness desired, and thereaftersubjecting the parchmentized sheets to the action-of a solvent for thecellulose ester whereupon the solvent displaces the water in the poresand causes a film of the'cellulose ester to form in the parchmentmembrane.

8. The process of making a paper product which comprises addingcellulose acetate to the paper and rag fibres prior to the Fourdriniermachine, processing the paper in the usual manner, parchmentizing thepaper, superimposing the sheets to obtain the thickness desired, andthereafter subjecting the parchmentized sheets to the action of asolvent for the cellulose acetate whereupon the solvent displaces thewater in the pores and causes a film of the cellulose acetate to form inthe parchment membrane.

9. A parchmentized paper product comprising a cellulose ester intimatelydispersed throughout the paper and rag fibres.

10. A parchmentized paper product comprising cellulose acetateintimately dispersed throughout the paper and rag fibres.

JAMES MoINTOSH.

